1. Field of the Invention
The present invention generally involves the field of technology pertaining to the mechanical treatment of metal workpieces. More particularly, the invention relates to the universal rolling of shaped metal members, especially steel rails and the like.
2. Description of the Prior Art
A conventional mill for rolling various shaped metal members, such as rails, girders, groove-and-tongue pilings, U-shaped channels, and the like, typically involves directing the member along a processing or rolling line. The initial upstream point of the line includes an oven for heating the semi-product, such as a bloom, ingot or the like. Proceeding downstream along the line, in sequential order, are a first set of reversing roughing stands for shaping the metal blank, a second reversing or intermediary set including at least one universal stand and an edger which can be moved in a direction perpendicular to the longitudinal axis of the line in order to remove same entirely out of the line, and a universal finishing stand for imparting the final shape to the member.
The universal finishing stand of a conventional rolling line is normally disposed at a considerable distance from the second reversing or intermediary set, with the distance exceeding the length of the longest shaped section being processed in the line. This distance may be on the order of a hundred meters in conventional practice. Because of this large distance, it has been proposed in the making of girders by universal rolling to move the universal finishing stand closer to the intermediary set in order to reduce construction costs by forming a single set of stands which consist of a first reversing universal stand, a second reversing edger and a first universal finishing stand. The rolled girder shall pass several times through this set of stands before they arrive at a transfer table for cutting to the desired length.
In one example of a known rolling procedure, a girder blank is consecutively rolled during a first pass from upstream to downstream by the reversing universal stand and the reversing edger, during a second pass from downstream to upstream by the reversing edger and the reversing universal stand, and during a third pass from upstream to downstream by the reversing edger and the universal finishing stand. During this procedure, the universal finishing stand is not utilized during the first and second passes, so that the rolled blank must be freely passed in sequence at the universal finishing stand. There are two known proposals for accommodating this latter requirement. First, the rolls of the unused stand may be separated, but this technique prevents maintaining the three-set adjustment in the finishing pass and is incompatible with utilizing the entry and exit guides of rolls provided specifically in a rail finishing stand. Moreover, the nature of the shape of a rail blank, especially the height of the rail head, requires a greater roll separation than for another type of blank, such as a girder blank. Second, it is also known to remove the universal stand from the rolling line in a direction perpendicular to the longitudinal axis of the line. However, this solution is also disadvantageous since it would be required to move the stand entirely out of the rolling line between the prior pass and the finishing pass, resulting in prohibitive loss of time and reduction in the overall efficiency of the rolling operation.